Miniature furniture 3D printed using ink made from recycled wood

Recycled wood can be turned into an ink for 3D printing, which could offer a more sustainable way to manufacture furniture or even build houses.

“Wood has been used for building and structural purposes for centuries,” says Muhammad Rahman at Rice University in Texas. But working with the material isn’t especially efficient, as chiselling it down to size can result in lots of waste.

To make use of this leftover material, Rahman and his colleagues split it into lignin and cellulose – molecules that are key to the stiff structure of wood – and these were broken down to form nanofibres and nanocrystals. They then recombined the cellulose and lignin with water to make a clay-like substance that could be used as an ink.

The researchers used this substance to 3D print objects by forcing it through a nozzle and building up layers of ink.

To boost the strength of the 3D-printed objects, the team freeze-dried them to remove moisture and then quickly heated them up to 180°C (356°F) to make the lignin soften and fuse with the cellulose.

“We can actually mimic all the visual, textural and olfactory properties of natural wood,” says Rahman. The product was found to be nearly six times more durable than natural balsa wood in compression tests, and up to three times as flexible in bending tests.

So far, the researchers have managed to create miniature furniture and honeycomb structures using the ink, but they hope it could eventually be used to build larger objects, such as houses.

“We need to rethink how we can make structures without cutting down trees,” says Rahman. “If we can recycle waste wood using 3D printing instead of conventional manufacturing, that would be a good step forward.”